Combustion chamber for engines



March 11, 1958 P. F. KEYDEL ETAL 2,826,185

I COMBUSTION CHAMBER FOR ENGINES v Filed Aug. 25, 1954 INVENTORSATTORNE! ited States Patent "'0 COMBUSTION CHAMBER FOR ENGINES Paul F.Keydel and George C. Trevarthen, Detroit, Mich., assignors to GeneralMotors Corporation, Detroit,

Mich, a corporation of Delaware Application August 25, 1954, Serial No.452,092

4 Claims. (Cl. 123-191) I This invention relates to combustion chambersfor engines and has particular relation to combustion chambersespecially applicable foremployment in four stroke cycle, spark ignited,internal combustion engines for automotive and other uses.

It is proposed to provide a combustion chamber that willoperate smoothlyand 'efliciently at compression ratios exceeding 8 to 1, that may .beemployed with a piston of symmetrical and balanced design, thatwillembody only-plane surfaces and surfaces of rotation and that may beeasily and accuratelymachined and otherwise manufactured-sothat thevolumeof all combustion chambers employed in any engine will be the samewithin close limits.

It is also proposedto provide a combustion chamber in which a firingchamber willbeformed at one side of the cylinder and at one side of theinlet and exhaust valves in the head of the cylinder and in suchposition that the spark plug may be. located substantially in the middleof thecharge compressed within the firing chamber. The firing ichambercommunicates at one side thereof with a minimum mechanical clearancespace extending throughout approximately half of the cross sectionalarea of. the cylinder. The volume of. the charge compressed in theclearance. space will be a considerable portion of the total volumeofthe charge and will confine the last part of the charge to burn in aspace where the surface area to volume ratio is relatively high.

In the drawing:

1 Figure 1 is a fragmentary cross sectional .view of a multicylinderorother engine having combustion chambers embracing the principles of theinvention.

Figure 2 is a fragmentary crosssectional view of the enginetakensubstantially in? the plane of line 2-2- on Figure 1 andillustrating particularly the head end of the piston employed in onecylinder of the engine.

Figure 3 is a fragmentary cross sectional view of the engine disclosedby Figure 1 and is taken-substantially in the plane of: line; 3-3 onFigure 1 looking in the direction of the arrowsthereon.

The engine 10 may be a multicylinder engine of-any design and mayinclude a liquid cooled cylinder block 11 and head 12. The block 11 mayinclude one ormore cylinders 13 in which pistons 14 are adapted toreciprocate during the operation of the. engine. The block 11 may beformed in such a way as to provide an ,upper wall 416, theouterusurface. of. which is arplanesurface perpendicular to the axesof'the cylinders 13 and at which the plane end surfaces .17 of thepistons 14 may terminate at the outer dead center positions of thepistons 14 within the cylinders 13. The head 12 also may have a lowerwall 18 having a plane outer surface which is also normal to the axes ofthe cylinders 13. The head 12 may be secured to the block 11 on a gasket19 engaging the plane surfaces of the wallsjlqa and 1d.

The combustion chamber 21' for each cylinder of the engine may be formedby providing a cavity 22 in the head .12 and in such manner as to form afiring chamber 23 at one side of the cylinder and a minimum mechanicalclearance space '25 at the opposite side of the cylinder, :Whenthepiston ,14 is at; outer. dead center posi- ".2 tion within the cylinder.The cavity 22 may be formed in .any desired manner but it ispreferred toform the cavity in. such. manner that it maybe easily machined .orotherwise finished to exact dimensions so that each combustion chamber21 withinthe engine 10. may, have substantially the same volume. ;.Itis, therefore, proposed to form the cavity' 22,in,such manner as toprovide a planev end, surface 24..and.oppositely disposed fragmentarytoroidal side surfaces 26 and 27. Thesurerably a fragment of a;frustoconical or rectilinear surfaceof revolution with the larger end thereof.merging .with..the.sur face 26 and the smaller end. thereof merg- .ingwith the outer. end. of the cylinder 13'throughout approximately half ofthe cylinder 13 and atone side of, thecylinder 13. .Thecavity 22 may beformed by a tool haying a cross sectionalconfiguration in a planethrough the axis of rotation thereof. substantiallyacorresponding to thesurfaces 24, 26 and 27. The tool may be rotated. about an .axisperpendicularto-the surface 24 and the axis may move laterally orrotationally during the rotation of the tool.

. It will be apparent that. the toolwill very accurately machine. thecavity 22 sothat allof the cavities for the cylinders of thevengine-mayenclose substantially equal volumesof compressed charge.

, It is. proposed to locate'the inlet and exhaust yalves 28 and 29respectively for each cylinder of the engine -in the head of theengineand' in such manner that the valves will extend substantiallyacross a idiametenof each cylinder with the inner surfaces of the.yalvessubstantially in the plane .of the surfaces 24. .Undensuchcircumstances it will be possible to employ the largest possible sizesof valves with the inlet valve .28- bei ng somewhat larger than'theexhaust valve .29. for each cylinder of the engine.

The inlet and exhaust valves 28and 29 are adapted to open and closeinlet and exhaust passages-48 and 49 whichare formed in the head 12 foreachcylinder of the engine.

surface of the lower wall 18 will extend inwardly over a considerablepart of the end of the cylinder 13. Under such circumstances. theadjacent surface of the head .12 in directly opposed relation to the endof the cylinder 13 of the engine will comprise a noimally disposed planesurface outside the chord and the sloping and arcuate surfaces 24, 26and 2'7.

It is preferred .to employ a piston with the combustion chamber 21having a projection 31 extending from the plane end surface 17 thereofand having plane side Walls 32 and 33 which intersect substantiallyalong a diameter of the cylinder 13 and which slope at equal angles withrespect to the end surface 17. The slope of the surfaces 32 and33'may bethe same as the slope of the surface 24 with the surface 32 being spacedfrom the surface 34 so as to provide a part of the minimum mechanicalclearance space indicated at 25. It is also preferred that the axes ofthe stems of the valves 28 and 29 be located in a plane substantiallyparallel to the line of intersection of the surfaces 32 and 33. Further,it is preferred to make the surface 26 of such extent that the inneredge of the surface will intersect the end of the cylinder 13substantially atthe diameter of thecylinder 13 so that the surface '26will curve inwardly at the 'opposite'ends ofthe asaarss valves 28 and 29and will merge with the inner surfaces of the valves 28 and 29substantially in the plane of the ends of the valves and the surface 24.In order to provide for the maximum size for the valves 28 and 29 it isproposed to recess the surfaces 24 and 26 as is indicated at 34 so thatthe seats for the valves may be formed outwardly slightly beyond thesurface 24 and so that clearance may be provided at the ends of thevalves and within the surface 26. It is proposed to form the surfaces atthe ends of the projection 31 as curved surfaces 36 which are spacedfrom the surface 26 by an amount substantially equal to the thickness ofthe mechanical clearance space 25. It is proposed to locate the sparkplug 37 for each cylinder of the engine in such manner that it willproject into the firing chamber 23 substantially in the middle of thefiring chamber. This may be done by disposing the spark plug at such anangle that the spark gap between the ignition terminals 38 of the sparkplug will be substantially on a diameter of the cylinder normallyintersecting the plane of the stems of the valves and on the curved linebetween the surfaces 24 and 26. The head may be relieved as is indicatedat 39 by a cone shaped surface concentric with the axis of the plug andextending towards the valves, to prevent the formation of a pocketwithin the spark plug and adjacent the terminals thereof.

With such construction it will be apparent that the larger part of thecharge which is compressed within the firing chamber 23 will be locatedin a relatively compact chamber with the spark gap between the ignitionterminals of the spark plug in position so that the charge will burnrapidly in all directions from the end of the plug thereby burning thegreater part of the charge in a relatively short time. The part of thecharge in the clearance space will commence to burn when the burning ofthe charge in the firing chamber 23 is substantially completed and willcontinue to burn thereafter until the burning ends at the opposite sideof the cylinder, Notwithstanding the increase in density and temperatureof the last part of the charge to burn within the clearance space 25 itwill be possible to burn relatively low octane fuel at high compressionpressures and without detonation, due to the relatively large surfacearea to volume ratio in the mechanical clearance space 25. It will benoted that the mechanical clearance space 25 extends substantiallythroughout one-half of the area of the end of the piston 14 and thecylinder 13 thereby insuring that the part of the charge compressed inthe firing chamber 23 will be uniformly mixed and that the quality ofthe mixture will be suitable for burning at the highest possible rate.it will be noted that the part of the mechanical clearance space 25which is formed between the surface 32 and the surface 24 is in a planeincluding the spark gap between the terminals 3%. This will insure thatthe final blast of the charge being compressed will be directed towardthe spark gap between the terminals 38, thereby insuring that theterminals will be surrounded by a properly mixed part of the charge, theburning of which will commence as quickly as possible after ignitionoccurs.

We claim:

1. A combustion chamber for engines having a cylinder and a head andhaving a piston adapted to reciprocate within said cylinder, saidcombustion chamber being formed by a cavity in the head having a planeend surface intersecting the end of the cylinder on a chord extendingacross said cylinder, said cavity forming a firing chamber at one sideof the cylinder, said piston being formed at the end thereof to providea plane end surface disposed in uniformly spaced relation to said headbeyond said chord and having a projection extending from said piston endsurface, said projection being formed by obliquely disposed planesurfaces intersecting within said cavity substantially on a diameter ofsaid cylinder and with one of said surfaces being disposed insubstantially parallel relation to said plane end surface of saidcavity.

2. An engine comprising a cylinder having a piston adapted toreciprocate therein and a head adapted to close the end of said cylinderbeyond said piston and having a combustion chamber formed thereinbetween said head and said piston and said cylinder, said combustionchamber being formed to include a cavity extending into said head andhaving an end wall disposed obliquely with respect to the axis of saidcylinder, said piston being formed to provide a projection at the endthereof extending into said cavity and having a plane wall surface onone side of said projection extending in substantially parallel relationto said end wall of said cavity, said plane wall side surface of saidprojection being formed to extend toward one side of said cylinder froma line forming a diameter of said cylinder, said projection on saidpiston being formed to extend from a plane end surface forming the outerend of said piston and disposed normally to the axis of said cylinder.

3. An engine having a cylinder with a piston adapted to reciprocatetherein and having a head for closing the end of said cylinder andcomprising, a combustion chamber formed between said head and saidpiston and including a firing chamber formed in said head and having anobliquely disposed end wall and oppositely disposed toroidal side walls,said piston being adapted to extend within said cavity and beingsymmetrical on opposite sides of a diameter of said cylinder and havinga side wall disposed in substantially parallel relation to said end wallof said cavity, a pair of inlet and exhaust valves disposed in said headand opening into said end wall and extending across said cylindersubstantially on a diameter of said cylinder, and a spark plugprojecting into said cavity with the ignition terminals thereofprojecting through said obliquely disposed end wall in directly opposedrelation to the space between said piston side wall and said end wall ofsaid cavity.

4. A combustion chamber for engines comprising a piston adapted toreciprocate therein, a head for said piston having a lower wall adaptedto be secured to the end of said cylinder, said lower wall being formedto provide a plane surface adjacent the end of said cylinder disposed innormal relation to the axis of said cylinder, a cavity formed in saidhead and including a plane end surface intersecting said plane lowersurface of said head and including oppositely disposed toroidal sidesurfaces, said side surfaces being surfaces of revolution formed aboutan axis perpendicular to said end surface, said piston being formed toprovide an end wall having a projection extending into said cavity, saidprojection being formed by oppositely disposed side surfacesintersecting substantially on a diameter of said cylinder and beingobliquely disposed with respect to said cylinder, one of said pistonside surfaces being parallel to said plane end surface and forming aminimum mechanical clearance space with said plane end surface when saidpiston is at outer dead center position in said cylinder, a pair ofinlet and exhaust valves opening through said plane end surface of saidcavity and into the central part of said cylinder, and a spark plugprojecting through said head with the terminals thereof disposed betweensaid valves and in opposed relation to said mechanical clearance space,one of said oppositely v disposed toroidal surfaces of said cavity beingadapted to substantially merge with the outer end of said cylinderthroughout substantially one half of the peripheral edge of saidcylinder.

References Cited in the file of this patent UNITED STATES PATENTS ,098Fedden Mar. 30, 1926 35 Swaine May 12, 1942 FOREIGN PATENTS 51 AustraliaMay 19, 1931

